Flange-free venturi nozzle insert

ABSTRACT

A flange-free venturi element for use in producing differential pressure for measurement of fluid flow in a conduit which is adapted for welded insertion into a conduit. The insert also has special passageway means around each end of the inlet-outlet cone portions of the venturi and through a supporting web to assist in balancing pressure differences during normal operation as well as during a possible &#39;&#39;&#39;&#39;choke&#39;&#39;&#39;&#39; or sonic flow condition such that the wall thickness of the pressure recovery cone can be of somewhat lesser thickness than would otherwise be required.

United States Patent 1 Pompa Nov. 27, 1973 FLANGE-FREE VENTURI NOZZLE INSERT [75] Inventor: Leonard A. Pompa, Stamford,

- Conn.

[75] Assignee: Universal Oil Products Company, Des Plaines, Ill.

[22] Filed: Dec. 6, 1971 21 Appl. No.: 205,234

[52] U.S. Cl. 138/44, 73/213 [51] Int. Cl. FlSd 1/02 [58] Field of Search 138/44, 40, 39, 37; 181/47; 73/213 [56] References Cited UNITED STATES PATENTS 1,850,030 3/1932 Pardoe 138/44 1,352,292 9/1920 3,326,041 6/1967 2,229,] 19 l/1941 Nichols et a] 138/44 Primary Examiner-George E. Lowrance Assistant Examiner-Steven M. Pollard AttorneyJames R. l-loatson, Jr. et al.

[57 ABSTRACT A flange-free venturi element for use in producing differential pressure for measurement of fluid flow in a conduit which is adapted for welded insertion into a conduit. The insert also has special passageway means around each end of the inlet-outlet cone portions of the venturi and through a supporting web to assist in 4 Claims, 5 Drawing Figures f: :JjjjjLZiiTi'i I FLANGE-FREE VENTURI NOZZLE INSERT The present invention relates to an improved form of flange-free venturi element for mounting in a fluid conducting conduit. More particularly, the invention is directed to a design where the entire internal venturi nozzle is supported from a transverse web with the holes or passageway means therethrough and, additionally, is sized to have small annular passageways around the ends of the cone sections such that pressure balancing aspects can be achieved.

Venturi nozzle sections are, of course, commonly inserted into pipes in order to have means for measurement of fluid flow rates through the particular pipe or zone. In addition, it is realized that venturi sections have been fabricated so that they may be readily inserted into a pipe length by having flanges at each end of a venturi section or by having a single support ring to be inserted between flanges at the ends of abutting pipe sections. For example, U. S. Pat. Nos. 3,273,390 and 3,326,041 show venturi tube designs and constructions adapted to be inserted into a pipe or conduit. With respect to these patents, it will be noted that the venturi nozzle, or element itself, is being mounted within an encompassing conduit such that a small annular space exists around at least one cone end of the element whereby fluid under pressure can enter. However, in contrast to the present improved design, there are no provisions for having pressure balancing holes or passageway means through the support or any barrier which may circumscribe the throat section of the venturi nozzle element. As a result, there have been no known equivalent means for effecting the balancing of pressure differences around the outside of an interiorly mounted venturi nozzle.

Briefly, it may be considered to be an object of the present invention to provide a venturi nozzle insert which has pressure balancing annular space provisions at each end thereof as well as pressure balancing passageway means through a ring support member around the exterior of the throat section, whereby there are both structural and operational advantages during either normal operating or choke conditions.

It may also be considered to be an object of the present invention to provide a welded or flange-free type of design and construction so that the venturi element can be inserted into piping in a manner to meet standard accepted codes, such as the A.S.M.E. Power Test Code. For example, pressure equipment for use in a nuclear power plant must be all welded and free of flange connections, as well as utilize full penetration or containment welds on all exterior wall surfaces.

In a broad aspect, the present invention embodies a flange-free venturi nozzle insert element suitable for welded installation into a fluid conduit, which comprises in combination, a venturi portion having a tapering inlet cone section, a throat section and a tapering pressure recovery cone section, a circumscribing web section around said throat section, and a conduit adapter section positioned concentrically around said venturi portion and connecting to said web section, whereby the latter together with said conduit adapter section will hold the venturi portion in a conduit connective with said conduit section, and the exterior diameter of both said inlet and pressure recovery cone sections are made slightly smaller than the inside diameter of said conduit, whereby to provide small fluid flow and pressure balancing annular passageways around said venturi sections, and said web section is provided with spaced passageway means having an area sized to be proportioned approximately equal to the upstream passageway and of lesser area than a downstream annular passageway, with such web passageways thereby effective to regulate normal flow and to lessen external pressure on the pressure recovery venturi section in the event of a sonic flow condition through said venturi element.

For instrumentation purposes, at least one pressure tap connection to the interior of the throat section will be made radially inwardly through the web or ring section which supports the venturi element with the conduit adapter section. Additional pressure tap connection to the main conduit may be made to a location around the exterior of the throat section, upstream from the insertable venturi element, or in any conventional manner that need not be considered a part of the present invention. Various shapes or configurations for the inlet cone and for the recovery cone sections may be provided to meet specific flow requirements. For example, the inlet portion may be curved in the nature of a portion of an ellipse to result in a long radius nozzle approach into the throat section with a length equivalent to a Herschel type venturi.

Also, inasmuch as the present element provides a flange-free design suitable for welded installation into a main conduit, then the end portions of the conduit adapter section which circumscribes the support ring section and the throat portion of the venturi element will have scarfed or'beveled ends which will permit full penetration containment welds, for attachment to the abutting end portions of the main conduit. As set forth in the embodiment, the ends of the inlet and outlet cone sections will have diameters or circumferences slightly less than the interior of the main conduit into which the venturi element will become inserted so that there may be space fora slight amount of expansion under differential temperature conditions, as well as spaces to provide for the pressure balancing aspects in accordance with the present invention.

Reference to the accompanying drawing and the following descriptionthereof will serve to illustrate one embodiment of the present invention as well as permit the setting forth of special operational and construction features and the advantages in connection therewith.

FIG. 1 of the drawing is a sectional elevational view showing the assembly of the entire venturi element and how it may be inserted into a main conduit section.

FIG. 2 of the drawing is a cross-sectional view through a throat portion of the venturi element in accordance with line 22 in FIG. 1 of the drawing.

FIG. 3 indicates diagrammatically the beveling and scarfmg which may be utilized at the end portions of the ring adapter section of the element whereby the latter may be readily connected into the main conduit section with containment welding.

FIGS. 4 and 4a show diagrammatically certain varying areas or proportional areas which may exist with respect to the annular passageway around the venturi sections and the passageway means in the intermediate ring section.

Referring now to FIGS. 1 and 2 of the drawing, there is indicated in the embodiment shown a central venturi nozzle element which is made up of a curved and tapering inlet cone section 1, a substantially straight throat portion 2 and an elongated tapering pressure recovery cone section 3. Circumscribing the central throat section 2 is a perpendicular web or support ring 4 which in turn is welded to and connects with a conduit adapter section 5. The latter is, of course, normally provided to be of the same diameter and wall thickness as the main conduit, such as 6, into which the venturi element will be inserted.

There is also indicated in the drawing the utilization of a boss or shoulder piece 7 welded to adapter section in alignment with the inner ring 4 such that there may be a pressure tap instrument connection into the interior of the throat section 2. Typically, there will be a drilled hole 8 carrying through the boss 7, adapter section 5, ring 4 and throat member 2 after the final welding of the various portions of the insert assembly. Also, as best shown in FIG. 2, a plurality of holes 9 are spaced around the circumference of ring section 4 such that there may be pressure balancing from one side of the venturi element to the other, as well as drainage, in the event of the use of the venturi element in a vertical orientation in a main conduit.

As hereinbefore noted, the inlet section 1 will be of a suitable design to meet desired flow conditions and need not be any one fixed design or size. The illustrated unit shows an inner surface 1 having a configuration equivalent to substantially one-fourth of the periphery of an elongated ellipse. It should be further noted that the circumference of inlet section 1 and the downstream circumference of pressure recovery cone section 3 is spaced slightly from the interior of the main conduit 6 so as to leave a small space S1 suitable to accommodate differential temperature expansion for the operating conditions to be encountered and in combination with holes 9 in ring member 4 provide a desired pressure balancing effect during normal operating or choke conditions. For example, during a normal operating period, some of the fluid stream may pass through the space S1 in a downstream direction as well as through holes 9 and carry into the space circumscribing cone section 3; however, since pressure can become equalized around the entire venturi element, there will be a null effect upon the operation of the venturi in measuring pressure differential and flow rate for the particular fluid passing through the conduit system. The holes 9 are, of course, necessarily large enough in diameter to provide suitable cross-sectional area to work with area S1 in choking and balancing fluid flow for normal flow conditions as well as for breakage or fault conditions. In other words, the mere placing of a small drain hole is not sufficient to provide the suit able balancing of pressures to insure a proper and efficient operation of the venturi insert as a flow measuring device.

It is also to be noted that by providing a suitable passageway area through ring section 4, such as by holes 9, there is a particular advantage obtained in enhancing the structural characteristics. For example, under choke conditions, such as where there may be a conduit breakage downstream from the venturi element, then for a given set of upstream conditions, there can be an increase in the linear velocity of the fluid stream through the throat until such velocity reaches that of sound. At the same time, under such a choke condition there can normally be a high pressure differential around a pressure recovery cone section of the venturi element tending to have the element deform or crush inwardly. However, it can be observed from a review of the present improved construction that, by virtue of having the spaces S1 and S2 at the respective ends of the venturi element and suitable passageway openings 9 through ring section 4 properly sized with relation to spaces S1 and S2, there can be a relief of differential pressure around cone section 3 and the resulting effect that such section may be made structurally less thick than normally required. In other words, under choke flow conditions in the throat of the main nozzle, holes 9 also choke and reduce pressure downstream around recovery cone 3.

As an illustration of conventional design with a 1000 psi upstream pressure, under choke condition, there would be 1,000 psi across the recovery cone wall tending to crush the cone in. With the holes 9 properly sized, the 1,000 psi would appear across these holes so that the external cone pressure would be essentially the same as the internal cone pressure. The sizing of areas S1 and S2 and holes 9 must be proportioned to provide the large choke effect under fault conditions but to not effect equilibrium under normal operating differential pressure conditions.

By way of further illustration, reference may be made to FIGS. 4 and 4a of the drawing where the spaces shown represent proportional areas such as provided by passageway S1, holes 9 and passageway S2. In all cases, S1 and S2 will provide for expansion clearances as well as spacings for pressure balancing. Also, in all cases total area 9 will be less than the downstream area S2 so as to provide a choke effect for normal flow and operational conditions. However, with respect to the upstream area S1, the area of 9 can be smaller, larger or about the same as the upstream area. Preferably, S1 and 9 will be provided to be about equal such that they can equally serve in choking flow and pressure for normal operating conditions. In FIG. 4, the area of 9 is smaller than S2 as well as S1, while in FIG. 4a, the area of 9 is again shown smaller than S2 but about equal to S1. The latter situation is generally considered preferable. The area of S2 should, of course, be adequate to permit rapid flow of atmospheric pressure from the downstream conduit, in the event of a breakage or choke flow conditions, such that there is pressure balancing around cone section 3 and the prevention of crushing. As hereinbefore noted, it was an important aspect of the present invention to permit thinner downstream cone sections in a venturi element and preclude crushing from line failure conditions.

With particular reference to the welded construction of the present venturi element, it may be noted that such element may be made of a varying number of pieces. For example, the interior venturi nozzle portion may be cast as one piece and machined or otherwise smoothed on the interior; however, preferably it will be made of at least two sections as indicated in FIG. 1 and a full penetration weld, such as 10, utilized to join the abutting end portions of sections 2 and 3. Typical structural welds are indicated in effecting the joining of ring section 4 with respect to the throat section 2 and to the external adapter conduit section 5. However, inasmuch as the latter section will be providing an external juncture with the main conduit 6 at each zone 11, there should be provided full penetration containment-welding at such juncture.

With specific reference to FIG. 3 of the drawing, there is indicated special beveling and scarfing for the ends of adapter conduit section 5 to be available for the containment welding connection with main conduit section 6. As noted briefly hereinbefore, for high pressure fluid containment welds, particularly for all conduits, pressure vessels or walls having an external surface, there should be conformance with pressure vessle codes such as the A.S.M.E. Boiler and Pressure Vessel Code or conformance with the A.S.M.E. Power Test Code, and the like, all of which will require full penetration welding by certified welders to insure leakproof and pressure-tight connection.

It is to be noted that the present drawing and venturi element embodiment should not be limiting in all aspects with respect to shape, proportion, and the like, nor shall the passageway means provided by holes 9 be limiting inasmuch as a lesser or greater amount of holes may well be utilized through ring section 4 to effect the desired cross-sectional area necessary for a particular sized venturi element. Still further, it is not intended to limit the length of the adapter section 5 to any one length, or proportion, with respect to the venturi element inasmuch as such an adapter section might well be made to have a length greater than that of the internal venturi nozzle portion. Still further, typically one support ring member 4 can be utilized to effect the support of the entire venturi element within an adapter conduit section and is preferable in that there are no problems with differentiation expansion between adjacent support members; however, the support ring member 4 may have a varying configuration and, of course, will vary in size depending upon the overall size of the venturi section and the size of the conduit to which the nozzle element is being inserted.

I claim as my invention:

1. A flange-free venturi nozzle insert element suitable for welded installation into a fluid conduit, which comprises in combination, a venturi portion having a tapering inlet cone section, a throat section and a tapering pressure recovery cone section, a circumscribing support ring section around said throat section, and a conduit adapter section positioned concentrically around said venturi portion and connecting to said ring section,

whereby the latter together with said conduit adapter section will hold the venturi portion in a conduit connective with said conduit section, the eitterior diameter of both said inlet and pressure recovery cone sections are made slightly smaller than the inside diameter of said conduit, whereby to provide small upstream and downstream fluid flow and pressure balancing annular passageways around said venturi inlet and recovery cone sections, and said ring section is provided with spaced passageway means to combine with the upstream passageway to choke fluid flow and control pressure drop around the element during normal flow conditions, said passageway means in said ringsection having an area smaller than said downstream annular passageway to thereby be effective to lessen external pressure on the pressure recovery venturi section in the event of a sonic flow condition through said venturi element, and said passageway means comprising holes which are spaced circumferentially around the throat section of the venturi element.

2. The venturi element of claim 1 is further characterized in that the upstream passageway and said passageway means through said ring section are about equal in area, whereby both such passageways are each of less area than that of the downstream annular passageway.

3. The venturi insert element of claim 1 further characterized in that at least one pressure tap connection and passageway is provided through said conduit adapter section, said support ring section and the throat section whereby such element may be used to provide differential pressure readings in the measurement of flow through the fluid conduit and the venturi nozzle element.

4. The venturi element of claim 1 further characterized in that each end portion of said conduit adapter section has beveled end portions adapted for a full penetration abutting welds connection with a main fluid conduit into which the element will be inserted.

=l= =l =i 

1. A flange-free venturi nozzle insert element suitable for welded installation into a fluid conduit, which comprises in combination, a venturi portion having a tapering inlet cone section, a throat section and a tapering pressure recovery cone section, a circumscribing support ring section around said throat section, and a conduit adapter section positioned concentrically around said venturi portion and connecting to said ring section, whereby the latter together with said conduit adapter section will hold the venturi portion in a conduit connective with said conduit section, the exterior diameter of both said inlet and pressure recovery cone sections are made slightly smaller than the inside diameter of said conduit, whereby to provide small upstream and downstream fluid flow and pressure balancing annular passageways around said venturi inlet and recovery cone sections, and said ring section is provided with spaced passageway means to combine with the upstream passageway to choke fluid flow and control pressure drop around the element during normal flow conditions, said passageway means in said ring section having an area smaller than said downstream annular passageway to thereby be effective to lessen external pressure on the pressure recovery venturi section in the event of a sonic flow condition through said venturi element, and said passageway means comprising holes which are spaced circumferentially around the throat section of the venturi element.
 2. The venturi element of claim 1 is further characterized in that the upstream passageway and said passageway means through said ring section are about equal in area, whereby both such passageways are each of less area than that of the downstream annular passageway.
 3. The venturi insert element of claim 1 further characterized in that at least one pressure tap connection and passageway is provided through said conduit adapter section, said support ring section and the throat section whereby such element may be used to provide differential pressure readings in the measurement of flow through the fluid conduit and the venturi nozzle element.
 4. The venturi element of claim 1 further characterized in that each end portion of said conduit adapter section has beveled end portions adapted for a full penetration abutting welds connection with a main fluid conduit into which the element will be inserted. 